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The CXC-chemokine CXCL4 interacts with integrins implicated in angiogenesis.

Aidoudi S, Bujakowska K, Kieffer N, Bikfalvi A - PLoS ONE (2008)

Bottom Line: We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner.Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration.As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U920, Talence, France. salouaaidoudi@yahoo.fr

ABSTRACT
The human CXC-chemokine CXCL4 is a potent inhibitor of tumor-induced angiogenesis. Considering that CXCL4 is sequestered in platelet alpha-granules and released following platelet activation in the vicinity of vessel wall injury, we tested the hypothesis that CXCL4 might function as a ligand for integrins. Integrins are a family of adhesion receptors that play a crucial role in angiogenesis by regulating early angiogenic processes, such as endothelial cell adhesion and migration. Here, we show that CXCL4 interacts with alphavbeta3 on the surface of alphavbeta3-CHO. More importantly, human umbilical vein endothelial cells adhere to immobilized CXCL4 through alphavbeta3 integrin, and also through other integrins, such as alphavbeta5 and alpha5beta1. We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner. Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration. As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

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Immobilized CXCL4 or CXCL4/CTF promotes αvβ3-CHO cell spreading, focal adhesion and stress fiber formation.A. αvβ3-CHO and mock-transfected CHO cells were plated for 4 h on coverslips that had been coated with (25 µg/ml) CXCL4, (25 µg/ml) CXCL4/CTF, (25 µg/ml) CXCL4/CTF-S, (100 µg/ml) fibrinogen and (100 µg/ml) poly-D-lysine. After washing, the cells are fixed. The degree of cell spreading is seen from the phase contrast micrographs (left side). Then the cells were permeabilized and stained to visualize focal adhesion (vinculin staining, green), and actin stress fibers (Rhodamin-Phalloidin staining, red) by confocal microscopy (right side). B. Effects of function-blocking anti-integrin antibodies and EDTA and RGD-, RGE-peptides on cell spreading to CXCL4 or CXCL4/CTF. αvβ3-CHO cells were incubated with 10 mM EDTA or 25 µg/ml of RGD- or RGE-peptides or 10 µg/ml anti-αvβ3 (LM609), before plating to coverslips coated with (25 µg/ml) CXCL4 or (25 µg/ml) CXCL4/CTF for 3 h at 37°C. Wells were washed with PBS, and cells were photographed.
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pone-0002657-g004: Immobilized CXCL4 or CXCL4/CTF promotes αvβ3-CHO cell spreading, focal adhesion and stress fiber formation.A. αvβ3-CHO and mock-transfected CHO cells were plated for 4 h on coverslips that had been coated with (25 µg/ml) CXCL4, (25 µg/ml) CXCL4/CTF, (25 µg/ml) CXCL4/CTF-S, (100 µg/ml) fibrinogen and (100 µg/ml) poly-D-lysine. After washing, the cells are fixed. The degree of cell spreading is seen from the phase contrast micrographs (left side). Then the cells were permeabilized and stained to visualize focal adhesion (vinculin staining, green), and actin stress fibers (Rhodamin-Phalloidin staining, red) by confocal microscopy (right side). B. Effects of function-blocking anti-integrin antibodies and EDTA and RGD-, RGE-peptides on cell spreading to CXCL4 or CXCL4/CTF. αvβ3-CHO cells were incubated with 10 mM EDTA or 25 µg/ml of RGD- or RGE-peptides or 10 µg/ml anti-αvβ3 (LM609), before plating to coverslips coated with (25 µg/ml) CXCL4 or (25 µg/ml) CXCL4/CTF for 3 h at 37°C. Wells were washed with PBS, and cells were photographed.

Mentions: Confocal analysis showed that immobilized CXCL4 or CXCL4/CTF promoted αvβ3-CHO cell spreading, focal adhesion and stress fibers formation (Fig. 4). These events were blocked in presence of EDTA or RGD peptides or with antibodies against αvβ3. In contrast, mock-transfected CHO cells did not appreciably spread and generate stress fibers of actin on CXCL4 or CXCL4/CTF. In addition, when αvβ3-CHO cells are plated on a scrambled peptide derived (CXCL4CTF-S), or on polylysine, they remained round, and failed to spread and to induce focal adhesion formation (Fig. 4). These results indicate that immobilized CXCL4 or CXCL4/CTF induces αvβ3-CHO cell spreading through αvβ3 integrins. Collectively, these results show that CXCL4 or CXCL4/CTF interacts with αvβ3 integrins and activates postligand binding event downstream to integrins, such as cell spreading.


The CXC-chemokine CXCL4 interacts with integrins implicated in angiogenesis.

Aidoudi S, Bujakowska K, Kieffer N, Bikfalvi A - PLoS ONE (2008)

Immobilized CXCL4 or CXCL4/CTF promotes αvβ3-CHO cell spreading, focal adhesion and stress fiber formation.A. αvβ3-CHO and mock-transfected CHO cells were plated for 4 h on coverslips that had been coated with (25 µg/ml) CXCL4, (25 µg/ml) CXCL4/CTF, (25 µg/ml) CXCL4/CTF-S, (100 µg/ml) fibrinogen and (100 µg/ml) poly-D-lysine. After washing, the cells are fixed. The degree of cell spreading is seen from the phase contrast micrographs (left side). Then the cells were permeabilized and stained to visualize focal adhesion (vinculin staining, green), and actin stress fibers (Rhodamin-Phalloidin staining, red) by confocal microscopy (right side). B. Effects of function-blocking anti-integrin antibodies and EDTA and RGD-, RGE-peptides on cell spreading to CXCL4 or CXCL4/CTF. αvβ3-CHO cells were incubated with 10 mM EDTA or 25 µg/ml of RGD- or RGE-peptides or 10 µg/ml anti-αvβ3 (LM609), before plating to coverslips coated with (25 µg/ml) CXCL4 or (25 µg/ml) CXCL4/CTF for 3 h at 37°C. Wells were washed with PBS, and cells were photographed.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2481302&req=5

pone-0002657-g004: Immobilized CXCL4 or CXCL4/CTF promotes αvβ3-CHO cell spreading, focal adhesion and stress fiber formation.A. αvβ3-CHO and mock-transfected CHO cells were plated for 4 h on coverslips that had been coated with (25 µg/ml) CXCL4, (25 µg/ml) CXCL4/CTF, (25 µg/ml) CXCL4/CTF-S, (100 µg/ml) fibrinogen and (100 µg/ml) poly-D-lysine. After washing, the cells are fixed. The degree of cell spreading is seen from the phase contrast micrographs (left side). Then the cells were permeabilized and stained to visualize focal adhesion (vinculin staining, green), and actin stress fibers (Rhodamin-Phalloidin staining, red) by confocal microscopy (right side). B. Effects of function-blocking anti-integrin antibodies and EDTA and RGD-, RGE-peptides on cell spreading to CXCL4 or CXCL4/CTF. αvβ3-CHO cells were incubated with 10 mM EDTA or 25 µg/ml of RGD- or RGE-peptides or 10 µg/ml anti-αvβ3 (LM609), before plating to coverslips coated with (25 µg/ml) CXCL4 or (25 µg/ml) CXCL4/CTF for 3 h at 37°C. Wells were washed with PBS, and cells were photographed.
Mentions: Confocal analysis showed that immobilized CXCL4 or CXCL4/CTF promoted αvβ3-CHO cell spreading, focal adhesion and stress fibers formation (Fig. 4). These events were blocked in presence of EDTA or RGD peptides or with antibodies against αvβ3. In contrast, mock-transfected CHO cells did not appreciably spread and generate stress fibers of actin on CXCL4 or CXCL4/CTF. In addition, when αvβ3-CHO cells are plated on a scrambled peptide derived (CXCL4CTF-S), or on polylysine, they remained round, and failed to spread and to induce focal adhesion formation (Fig. 4). These results indicate that immobilized CXCL4 or CXCL4/CTF induces αvβ3-CHO cell spreading through αvβ3 integrins. Collectively, these results show that CXCL4 or CXCL4/CTF interacts with αvβ3 integrins and activates postligand binding event downstream to integrins, such as cell spreading.

Bottom Line: We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner.Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration.As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U920, Talence, France. salouaaidoudi@yahoo.fr

ABSTRACT
The human CXC-chemokine CXCL4 is a potent inhibitor of tumor-induced angiogenesis. Considering that CXCL4 is sequestered in platelet alpha-granules and released following platelet activation in the vicinity of vessel wall injury, we tested the hypothesis that CXCL4 might function as a ligand for integrins. Integrins are a family of adhesion receptors that play a crucial role in angiogenesis by regulating early angiogenic processes, such as endothelial cell adhesion and migration. Here, we show that CXCL4 interacts with alphavbeta3 on the surface of alphavbeta3-CHO. More importantly, human umbilical vein endothelial cells adhere to immobilized CXCL4 through alphavbeta3 integrin, and also through other integrins, such as alphavbeta5 and alpha5beta1. We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner. Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration. As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

Show MeSH
Related in: MedlinePlus